To minimize Kvco variation, you could use a lot of switching bands. You'll find up to 8bits worth of bands in published VCO's if I'm not mistaken (which means you need to put in 256 swiched caps). Could be it was 6 bits, which would mean 64 switched capacitors.
And 800MHz tuning: doesn't say anything about difficulty; it's the percentage that counts. If you're trying to do 50-850MHz with one LC VCO I wish you good luck
. If it is around 17GHz, it shouldn't be that hard....
wizz